The Northern parties have been given a fresh warning that Mr Tony Blair's willingness to seek "an alternative way forward" in the event of failure at next week's Leeds Castle talks "is not an idle position".
The warning came last night after DUP deputy leader Mr Peter Robinson appeared to cast doubt on the prospects for the planned three-day negotiation as he pressed Northern Ireland Secretary Mr Paul Murphy for assurances about the future role of the Stormont Assembly.
Asking what the position would be "if the talks do not succeed" because paramilitaries refused to decommission and cease their activities "completely", Mr Robinson told MPs he assumed the British government would not wish to see the Assembly fall. In that event, he suggested, the choice would be between having "an Assembly with no executive, or an executive without Sinn Féin".
Side-stepping all invitations to say what might be in any "Plan B", Mr Murphy insisted the government was proceeding on the basis that the talks would succeed, and would not simply provide "a staging post" to a further negotiation.
In exchanges during Northern Ireland Questions in the Commons, Mr Murphy maintained that "recent meetings with all the parties" had given him confidence "that agreement is within our grasp".
He also echoed Mr Blair's apparent determination, repeated at his Downing Street press conference on Tuesday, that next week would mark "the moment of decision for the peace process".
Last night senior Whitehall sources said the parties would be mistaken to think Mr Blair's "an idle position". He was determined "progress must be made and momentum maintained".
The SDLP, meanwhile, has again demanded that the governments act as "the custodians of the Good Friday agreement".
Mr Seamus Mallon said, while welcoming "the conversion of DUP poachers who would become chief game-keepers", this could not be at the expense of the agreement.
Mr Murphy told Mr Mallon, and later the former SDLP leader Mr John Hume, that "the fundamentals of the Good Friday agreement are the basis" on which next week's talks would take place.
Ulster Unionist leader Mr David Trimble told Mr Murphy the British government would be left with "no credibility" if it was to be found "still hanging around" Mr Blair's famous "fork in the road" following the Leeds Castle talks.